1. Field of the Invention
The invention generally relates to a projection apparatus, and more particularly, to a projection apparatus able to reduce stray light.
2. Description of Related Art
When a projection apparatus performs image projection, usually, the light valve thereof converts an illumination beam into an image beam and reflects the image beam to a projection lens, where the image beam is projected by the projection lens onto a screen to form images. Along with the thin-shape design tendency of the volume of a projection apparatus however, distances between optical components inside the projection apparatus become shorter and shorter. As a result, when a beam is transmitted into a projection apparatus, stray light is easily produced since the distances between the optical components thereof are too close.
Taiwan Patent No. 1325091 discloses a projection apparatus, and the projection apparatus includes an illumination system, a digital micro-mirror device (DMD), a projection lens, and a total internal reflection prism (TIR prism), wherein the illumination system includes a plurality of lenses. Taiwan Patent No. 1292509 discloses another projection apparatus, and the projection apparatus has an illumination system, a DMD, and a projection lens, wherein the illumination system includes a light source, a light integrator (LID), lenses, and a reflective plate. In addition, Taiwan Patent No. M314352 discloses a projection display apparatus, and the projection display apparatus includes a light source, a light valve, a set of prisms, and a projection lens. The set of prisms comprises a first prism and a second prism. In terms of reducing stray light however, the efficiencies of the above-mentioned conventional architectures are very limited.